The nuclear hormone receptor superfamily of ligand activated transcription factors is present in various tissues, and responsible for a multitude of effects in these tissues.
The nuclear receptor (NR) superfamily presently comprises approximately 48 different proteins, most of which are believed to function as ligand activated transcription factors, exerting widely different biological responses by regulating gene expression. Members of this family include receptors for endogenous small, lipophilic molecules, such as steroid hormones, retinoids, vitamin D and thyroid hormone.
The nuclear receptor (NR) superfamily includes the steroid nuclear receptor subfamily, such as the mineralocorticoid receptor (MR) (or aldosterone receptor), the estrogen receptors (ER), ER alpha and ER beta, the androgen receptor (AR), the progesterone receptors (PR), glucocorticoid receptors (GR) and others. Also closely related in structure are the estrogen related receptors (ERRs) ERR-alpha, ERR-beta and ERR-gamma. The steroid nuclear receptors perform important functions in the body some of which are related to the transcriptional homeostasis of electrolyte and water balance, growth, development and wound healing, fertility, stress responses, immunological function, and cognitive functioning. The effects may be mediated by cytosolic or nuclear events. The effects may be mediated by cytosolic or nuclear events. Accordingly, compounds that modulate (i.e. antagonize, agonize, partially antagonize, partially agonize) the activity of steroid nuclear receptors are important pharmaceutical agents that have specific utility in a number of methods, as well as for the treatment and prevention of a wide range of diseases and disorders modulated by the activity of steroid nuclear receptors.
Members of the steroid nuclear receptor sub-family exhibit significant homology to each other and possess closely related DNA and ligand binding domains.
Given the close similarity in ligand binding domains of the steroid nuclear receptors, it is not surprising that many naturally occurring and synthetic molecules possess the ability to modulate the activity of more than one steroid nuclear receptor.